php - Use array_diff_assoc() or get difference of multidimensional arrays

Question

I've been struggling with what I think should be a really easy issue for sometime now and just can't work out the answer.

I have two arrays and these arrays contain information about id, linklabel and url in the following format:

$pageids
--------
Array ( 
[0] => Array 
( [id] => 1 
  [linklabel] => Home 
  [url] => home )

[1] => Array 
( [id] => 2 
  [linklabel] => Graphic Design 
  [url] => graphicdesign ) 

[2] => Array 
( [id] => 3 
  [linklabel] => Other Design 
  [url] => otherdesign ) 

[3] => Array 
( [id] => 6 
  [linklabel] => Logo Design 
  [url] => logodesign ) 

[4] => Array 
( [id] => 15 
  [linklabel] => Content Writing 
  [url] => contentwriting ) 
) 


$parentpage
-----------
Array ( 
[0] => Array 
( [id] => 2 
  [linklabel] => Graphic Design 
  [url] => graphicdesign ) 

[1] => Array 
( [id] => 3 
  [linklabel] => Other Design 
  [url] => otherdesign ) ) 

I'm now trying to compare these two in order to find the information that is in $pageids but NOT in $parentpage - this will then make up another array called $pageWithNoChildren. However when I use the following code:

$pageWithNoChildren = array_diff_assoc($pageids,$parentpage);

The array_diff_assoc() runs on the first level of the arrays and therefore sees that both $pageids and $parentpages have a [0] and [1] key so it ignores them and returns all the information from $pageids from [2] onwards. However I want it to look at the content of the nested arrays and compare those e.g. I need it to see which id, linklabel and url are in $pageids and not in $parentpages and return those values.

How can I get the array_diff_assoc() to run on the keys of the nested arrays and not the keys of the first arrays so the final result is an array that contains the contents of the [0], [3] and [4] arrays from $pageids?

Answer 1

To check multi-deminsions try something like this:

$pageWithNoChildren = array_map('unserialize',
    array_diff(array_map('serialize', $pageids), array_map('serialize', $parentpage)));

• array_map() runs each sub-array of the main arrays through serialize() which converts each sub-array into a string representation of that sub-array
  • the main arrays now have values that are not arrays but string representations of the sub-arrays
• array_diff() now has a one-dimensional array for each of the arrays to compare
• after the difference is returned array_map() runs the array result (differences) through unserialize() to turn the string representations back into sub-arrays

Q.E.D.